The EHB....In all its glory...

The extensor hallucis brevis : An overlooked "miracle worker"

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The Extensor Hallicus Brevis, or EHB as we fondly call it is an important muscle for descending the distal aspect of the 1st ray complex (1st metatarsal and medial cunieform) as well as extending the 1st metatarsophalangeal joint. It is in part responsible for affixing the medial tripod of the foot to the ground.  Its motion is generally triplanar, with the position being 45 degrees from the saggital (midline) plane and 45 degrees from the frontal (coronal) plane, angled medially, which places it almost parallel with the transverse plane. With pronation, it is believed to favor adduction (1).

It arises from the anterior calcaneus and inserts on the dorsal aspect of the proximal phalynx. It is that quarter dollar sized fleshy protruding, mass on the lateral aspect of the dorsal foot.  The EHB is the upper part of that mass. It is innervated by the lateral portion of one of the terminal branches of the deep peronel nerve (S1, S2), which happens to be the same as the extensor digitorum brevis (EDB), which is why some sources believe it is actually the medial part of that muscle. It appears to fire from loading response to nearly toe off, just like the EDB; another reason it may phylogenetically represent an extension of the same muscle (2-4).

Because the tendon travels behind the axis of rotation of the 1st metatarsal phalangeal joint, in addition to providing extension of the proximal phalynx of the hallux (as seen in the child above), it can also provide a downward moment on the distal 1st metatarsal (when properly coupled to and temporally sequenced with the flexor hallicus brevis and longus), assisting in formation of the foot tripod we have all come to love (the head of the 1st met, the head of the 5th met and the calcaneus).

Why is this so important?

The central axis of a joint (sometimes called the instantaneous axis of motion) is the center of movement of that articulation. It is the location where the motion will occur around, much like the center of a wheel, where the axle attaches. In an articulation, it usually involves one bone moving around another. Lets look at an example with a door hinge.

A hinge is similar to a joint, in that it has parts with is joining together (the door and the jamb), with a “joint” in between, The axis of rotation of the hinge is at the pivot rod. When the door, hinge and jamb are all aligned, it functions smoothly. Now imagine that the hinge was attached to the jamb 1/4” off center. What would happen? The hinge would bind and the door would not operate smoothly.

Now let’s think about the 1st metatarsal phalangeal joint. It exists between the head of the 1st metatarsal and the proximal part of the proximal part of the proximal phalanyx. Normally, because the head of the 1st metatarsal is larger than the heads of the lesser ones, the center of the joint is higher (actually,almost 2X as high; 8mm as opposed to 15mm). We also remember that the 1st metatarsal is usually shorter then the 2nd, meaning during a gait cycle, it bears the brunt of the weight and hits the ground earlier than the head of the 2nd.

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The head of the 1st metatarsal should slide (or should we say glide?) posteriorly on the sesamoids during dorsiflexion of the hallux at pre swing (toe off). It is able to do this because of the descent of the head of the 1st metatarsal, which causes a dorsal posterior shift of the axis of rotation of the joint. We remember that the head of the 1st descends through the conjoined efforts of supination and the coordinated efforts of the peroneus longus, extensor hallucis brevis, extensor hallucis longus, dorsal and plantar interossei and flexor hallucis brevis (which nicely moves the sesamoids and keeps the process going smoothly)(1, 5).

Suffice it to say, if things go awry, the axis does not shift, the sesamoids do not move, and the phalanyx crashes into the 1st metatarsal, causing pain and if it continues, a nice spur you can write home about!

Treating and needling this muscle is easy, as it is very accessible on the dorsum of the foot and due to the decreased receptor density, is not too uncomfortable. We like to needle the peroneus longus and short flexors as well, as they all have the function of lowering the head of the 1st ray. Check it out in this quick how to video.

1. Michaud T: Human Locomotion: The Conservative Management of Gait Related DisordersNewton Biomechanics; First Edition 2011

2. https://www.physio-pedia.com/Extensor_Hallucis_brevis

3. http://www.wheelessonline.com/ortho/extensor_hallucis_brevis

4. Becerro de Bengoa Vallejo R., Losa Iglesias M.E., Jules K.T.  Tendon Insertion at the Base of the Proximal Phalanx of the Hallux: Surgical Implications (2012)  Journal of Foot and Ankle Surgery,  51  (6) , pp. 729-733.

5. Zelik, K.E., La Scaleia, V., Ivanenko, Y.P. et al. Eur J Appl Physiol (2015) 115: 691. https://doi.org/10.1007/s00421-014-3056-x

Lets take another look at the tibialis posterior

As cinincians , we often needle and treat the tibialis posterior for posterior tibial tendon dysfunction, platar fasicits, patellofemoral joint pain, and a host of other conditions. Lets take a look at some of the anatomy and see why it is a big player in these conditions. 

The tibialis posterior takes its origin from the proximal posterior tibia, fibula and interosseous membrane. It is deep to the tricep surae and more superior than the flexors hallucis and didgitorum longus. The tendon descends medially, travels around the medial malleolus and divides into 3 portions: plantar, main and recurrent components. It inserts into all the tarsals and metatarsals 2-4.(1) Note that it DOES NOT insert into the 1st metatarsal. There must be a good reason for this, no?

The tibialis posterior acts to plantar flex and invert the foot as well as help eccentrically control eversion of the foot. It fires from initial conact to almost terminal swing. This assists in plantart flexion of the foot from initial contact to loading response, eccentric slowing of the foot during pronation from loading response to misdstance and concentric contraction to assist in and speed up supination from midstance to terminal stance.  When you look at the EMG studies for walking (2,3) , you will see that it starts ramping down activity just after midstance as the peroneus longus starts to ramp up more (firing from just after loading response to pre swing, with a bust of activity from midstance on). 

So, with all this talk, there has to be a reason, right? Think about this. In order to move forward in the gravitational plane and have high gear push off (ie, pushing off the base of the hallux), the 1st ray needs to descend to gain purchase on the ground (2,4, 5) . This is largely through the actions of the peroneus longus, extensor hallucis brevis and flexor digitorum brevis (6,7). The function of the peroneus longus should be obvious with its attachment to the base of the 1st metatarsal. The extensor hallucis brevis moves the axis of the 1st MTP downward when it contracts, as discussed here and here (8, 9). The flexor digitorum brevis moves the axis of metatarsalphalangeal joints 2-5 dorsally and posterior which effectively moves the axis of the head of the 1st metatarsal phalangeal joint ventral and anteriorly. This is requisite for you to have adequate hallux dorsiflexion of about 60 degrees to toe off normally. 

OK, so what about the tibialis posterior? 

Remember that the tib posterior attaches to most of the proximal bottom of the foot with the exception of the 1st metatarsal base? In the area of the 1st ray, the tib posterior attaches to the navicular. When it contracts, it will pull the navicular posterior and inferior, effectively rasing the base of (and lowering the head of) the 1st metatrsal. If it attached to the 1st metatarsal, its base would be pulled posterior and inferior which would raise the head of the 1st ray, exactly what we are trying NOT TO DO

Armed with this clinical tidbit, can you see how posterior tibial tendon dysfunction can be involved with so many foot and therefore lower kinetic chain problems? If you can’t descend the 1st ray, the foot will need to toe off its lateral aspect, with less effectiveness of the calcaneocuboid locking mechanism (more on that here (10) and here (11)), so problems with propulsion off of an “unlocked” foot. Can you see how the forefoot may be somewhat more everted in this situation? Can you see how this would contribute to more calcaneal eversion and sustained midfoot pronation from midstance through the rest of the gait cycle?  What muscle is sitauted to help maintain the arch as well as decelerate pronation? Tibialis posterior. What muscle will be called into play to assist the gastroc/soleus to help propel you forward? Tibialis posterior. You get the picture.

The tibialis posterior. An important player in the gait game. A great muscle to needle thatpays clinical dividends in more ways than you can imagine. 


1. Bubra PS, Keighley G, Rateesh S, Carmody D. Posterior Tibial Tendon Dysfunction: An Overlooked Cause of Foot Deformity. Journal of Family Medicine and Primary Care. 2015;4(1):26-29. doi:10.4103/2249-4863.152245.

 2. Michaud T. Foot Orthoses and Other Forms of Conservative Foot Care. Thomas Michaud Newton, MA 1993

3. ValmasseyR. Clinical Biomechanics of the lower extremities. Mosby, St Louis, Philadelphia. 101-107: 1996

4. Inman VT, Ralston HJ, Todd F. Human Walking. Baltimore, Williams and Wilkins, 1981

5. Scranton PE, et al. Support phase kinematics of the foot.  In Bateman JE, Trott AW (eds). The Foot and Ankle. New York, Thieme-Stratton, 1980

6. Perry J. Gait Analysis: Normal and Pathological Function. Thorofare, NJ, Slack 1992

7. The Pathokinesiology Service and the Physical Therapy Department. Observational Gait Analysis. Rancho Los Amigos National Rehabilitation Center Downey, CA 2001

8. https://tmblr.co/ZrRYjxFOn2hk

9. https://tmblr.co/ZrRYjxFSJ4Yz

10. https://tmblr.co/ZrRYjx1MjeIVN

11. https://tmblr.co/ZrRYjxToM8SI

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1st met pain in an orthotic?

This patient came in with pain at the base of the first metatarsal that she believed was related to her orthotic. The first picture shows the foots relationship to the orthotic. Notice how the sesamoid bones and distal aspect of the first metatarsal under lap the orthotic shell. In other words, the shell is longer than her foot. When she dorsiflexes her big toe, she’s hitting the distal of the orthotic.

The next view shows the orthotic with a typical first ray cutout. Notice how far forward the shell of the orthotic goes (next picture). I have placed a pen pointing to the area where the orthotic shell is too long.

In addition to reviewing her first ray descending exercises, a simple fix was to grind back the orthotic shell and be careful to bevel the edge so that it was not hitting the sesamoids and it did not impinge upon the descending first ray. I have placed a pen where the cut out now is (pre and post gluing in the pictures). The cork underlying the base of the first ray was also ground away (last picture)

A simple fix for a common problem. Make sure that your orthotic shell lengths fall just short of the 1st ray and not impinge on the sesamoids!

One way to correct an dysfunctional Extensor Hallucis Brevis

The Extensor Hallicus Brevis, or EHB  (beautifully pictured above causing the  extension (dorsiflexion) of the proximal big to is an important muscle for descending the distal aspect of the 1st ray complex (1st metatarsal and medial cunieform) as well as extending the 1st metatarsophalangeal joint.

Since this muscle is frequently dysfunctional, and is one of THE muscles than can lower the head of the 1st metatarsal, along with the peroneus longus and most likely the tibialis posterior (through its attachment to the 1st or medial cunieform), needling can often assist in normalizing function and works especially well, when coupled with an appropriate rehab program. Here is one way to needle it effectively. 

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The Calcaneo Cuboid Locking Mechanism

Do you know what this is? You should if you walk or run!

It is the mechanism by which the tendon of the peroneus longus travels behind the lateral malleolus of the ankle, travels underfoot, around the cuboid to insert into the lateral aspect of the base of the 1st metatarsal and adjacent 1st cunieform (see above)

For more cool info on the peroneus longus, see our blog post here.

When the peroneus longus contracts, in addition to plantar flexing the 1st ray, it everts the cuboid and locks the lateral column of the foot, minimizing muscular strain required to maintain the foot in supination (the locked position for propulsion). Normally, muscle strength alone is insufficient to perform this job and it requires some help from the adjacent articulations.

In addition, the soleus maintains spuination during propulsion by plantar flexing and inverting rear foot via the subtalar joint. This is assisted by the peroneus brevis and tertius which also dorsflex and evert the lateral column, helping keep it locked. Can you see why the peroneii are so important?

signs of a faulty calcaneo cuboid locking mechanism

  • weak peroneus longus, brevis and or tertius
  • excessive rear or midfoot pronation
  • low arch during ambulation
  • poor or low gear “push off”
  • subluxated cuboid

The calcaneo cuboid locking mechanism. Essential for appropriate supination and ambulation. Insufficiency, coming to a foot you will soon examine.

The Gait Guys. Improving your GQ (Gait Quotient) each and every day with every post we write.

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“I’ll plead the 1st … ."   More foot geek stuff from The Gait Guys.

The 1st Ray that is!

The "1st ray” consists of the 1st metatarsal and the medial cunieform, essentially the long bones associated with the big toe. It is a functional unit we often refer to when discussing foot biomechanics.

You have heard us speak of the 1st ray needing to descend to form the medial tripod of the foot (tripod review: head of 1st metatarsal, head of 5th metetarsal, center of calcaneus). This action depends to some degree on the competency of the peroneus longus, which attaches from the upper lateral fibula and the associates interosseous membrane; curves around the lateral malleolus, crosses under the foot and attaches to the base of the 1st metatarsal and medial cunieform. The tibialis posterior is supportive to this action. This action is opposed (or modulated, for every Yin there is a Yang; it’s all about balance) is the tibialis anterior, which attaches to the top of the base of the 1st metatarsal and 1st cunieform.

As a result, 1st rays can be elevated or depressed. (here is a latin term to impress your friends with: Metatarsus Primus Elevatus, or elevation/dorsiflexion of the 1st ray/metatarsal). Clinically, we see more that are elevated, resulting in a faulty (collapsing) medial tripod of the foot. The important thing is isn’t necessarily its position, but rather its flexibility. The inflexible ones (isn’t it always?) are the problem children, because they result in altered (notice I didn’t say bad) biomechanics. The further we move from ideal, the closer we seem to move to some compensation pattern. The flexible ones are still a problem but we can control and dampen their rate of flexible collapse.

Generally speaking, a plantar flexed 1st ray that is rigid, has a tendency to throw your center of gravity (an often your knee) to the outside of the foot tripod (think of a rigid cavus foot) and a dorsiflexed to the inside of the foot tripod. Sure, there are LOTS of other factors, but we are talking in generalities here.

Look carefully at the images above and note the position of the 1st metatarsal heads. In the top set, the 1st is depressed (or plantarflexed). In the bottom set they are elevated (or dorsiflexed). Cool, eh? 

NOTE: please refrain from using the term “dropped metatarsal”. Nothing gets dropped, it is correctly stated as plantarflexed (rigid or flexible).

Be on the look out for these on your clinical exam.

Ivo and Shawn. Bringing you one step closer to foot geekdom each day!

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